| Hole drilling of CFRP/Titanium alloy laminates is an important problem in aircraft assembly field.As CFRP and titanium alloy are both difficult-to-machine materials.the hole quality is poor and the tool is heavily worn.In order to solve the problems when drilling CFRP/Titanium alloy laminates,the tool wear mechanism and the cause of hole defects were investigated in this thesis.The drilling performance of TiSiC coated drill was researched when it was used to drill CFRP/TC4 titanium alloy laminates.The optimization experiment of coated drill’s point angle was also carried out.The main work and results are as follows:1.The influence of cutting parameter on TC4 titanium alloy drilling temperature and CFRP drilling thrust were analyzed by finite element method.The influence of spindle speed and feed rate on hole quality was researched through drilling experiments of TC4 titanium alloy and CFRP.Tool wear mechanism of carbide twist drills were analyzed when drilling these two materials.It would provide an experimental foundation for the high precision hole drilling of CFRP/TC4 titanium alloy laminates.2.The drilling experiment of CFRP/TC4 titanium alloy laminates was carried out by TiSiC coated drill.The cutting performance of TiSiC coated drill was studied compared with uncoated drill.The results show that coated drill could decrease drilling force of CFRP and titanium alloy,improve exit hole quality of TC4 titanium alloy and CFRP,reduce aperture error and prolong tool’s life.3.Based on TiSiC coated drill,the optimization experiment of point angle was carried out.Thrust force,coated tool wear,exit hole quality of CFRP/TC4 titanium alloy and hole wall quality were analyzed.The results show that the hole roughness of laminates and titanium exit hole burr height drilled by three kinds of coated tools were very low.However,in terms of tool durability and CFRP hole quality,the results obtained by coated drill with point angle of 135°are more better. |
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